title: Serum-free media for articular chondrocytes in vitro expansion.
abstract: BACKGROUND
  In vitro chondrocyte expansion is a major challenge in cell-based therapy for human articular cartilage repair. Classical culture conditions usually use animal serum as a medium supplement, which raises a number of undesirable questions. In the present study, two kinds of defined, serum-free media were developed to expand chondrocytes in monolayer culture for the purpose of cartilage tissue engineering.
  
  
  METHODS
  Bovine chondrocytes were expanded in serum-free media supplemented with fibroblast growth factor-2 and platelet-derived growth factor or fibroblast growth factor-2 and insulin-like growth factor. Expansion culture in a conventional 10% fetal bovine serum (FBS) medium served as control. Fibronectin coating was used to help cell adhesion in serum-free medium. Next, in vitro three-dimensional pellet culture was used to evaluate the chondrocyte capacity. Cell pellets were expanded in different media to re-express the differentiated phenotype (re-differentiation) and to form cartilaginous tissue. The pellets were assessed by glycosaminoglycans contents, collagen II, collagen I and collagen X immunohistological staining.
  
  
  RESULTS
  Chondrocytes cultured in serum-free media showed no proliferation difference than cells grown with 10% FBS medium. In addition, chondrocytes expanded in both serum-free media expressed more differentiated phenotypes at the end of monolayer culture, as indicated by higher gene expression ratios of collagen type II to collagen type I. Pellets derived from chondrocytes cultured in both serum-free media displayed comparable chondrogenic capacities to pellets from cells expanded in 10% FBS medium.
  
  
  CONCLUSIONS
  These findings provide alternative culture approaches for chondrocytes in vitro expansion, which may benefit the clinical use of autologous chondrocytes implantation.
authors.affiliation: McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Xin-xin
authors.initials: XX
authors.lastname: Shao
authors.forename: Neil A
authors.initials: NA
authors.lastname: Duncan
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.forename: Xin
authors.initials: X
authors.lastname: Fu
authors.forename: Ji-ying
authors.initials: JY
authors.lastname: Zhang
authors.forename: Chang-long
authors.initials: CL
authors.lastname: Yu
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology*; D002417:Cattle; D054337:Cell Dedifferentiation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D016895:Culture Media, Serum-Free; D005353:Fibronectins / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics
chemical_list: D016895:Culture Media, Serum-Free; D005353:Fibronectins; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human